feat: Enhance TV support and Daily Weather Forecast (w/ Air Quality)

- **Frontend (Flutter)**
    - Optimize for Google TV: Force Landscape mode, disable touchscreen requirement, and set TV Dashboard as default home.
    - Weather Widget:
        - Add Daily Max/Min temperature ('최고/최저').
        - Add Air Quality Index (AQI) with visual indicator ('미세먼지').
        - Increase font sizes and adjust layout to match Digital Clock style.
        - Implement 1-hour auto-refresh timer.
    - Model: Update WeatherInfo to support tempMin, tempMax, and aqi.

- **Backend (Node.js)**
    - Weather API (/api/weather):
        - Implement daily forecast aggregation logic (Seoul Time KST) to calculate accurate daily High/Low.
        - Integrate OpenWeatherMap Air Pollution API to fetch AQI.

flutter_app/lib/services/mock_data.dart

@@ -135,6 +135,9 @@ class MockDataStore {
   static WeatherInfo weather = const WeatherInfo(
     description: "clear sky",
     temperature: 12,
+    tempMin: 8,
+    tempMax: 15,
+    aqi: 2,
     icon: "01d",
     city: "Seoul",
   );